Sheet processing apparatus

ABSTRACT

In accordance with an embodiment, a sheet processing apparatus comprises a standby section configured to buffer a sheet; a processing section configured to receive sheets supplied from the standby section and execute a post processing on the sheets; a rotational shaft configured to rotate around an axis of rotation; a paddle arranged in the rotational shaft and configured to contact the sheet and move the sheets by rotating with the rotational shaft, the paddle being configured to slide the sheets on the processing section to a stopper for aligning the sheets; and a controller configured to control a rotational speed of the rotational shaft to rotate the paddle at a first speed, and control the rotational speed of the rotational shaft to rotate the paddle at a second speed slower than the first speed while the paddle contacts the sheets on the processing section for aligning.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of application Ser. No. 15/218,688filed on Jul. 25, 2016, the entire contents of which are incorporatedherein by reference.

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2015-250989, filed Dec. 24, 2015, theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a sheet processingapparatus for carrying out a post processing on a sheet on which animage is formed.

BACKGROUND

Conventionally, a sheet processing apparatus is known which executes apost processing such as a stapling processing on sheets loaded on aprocessing tray. In order to adjust deviation between the sheets loadedon the processing tray which are subjected to the post processing, thesheet processing apparatus includes a member for adjusting (horizontallyaligning) the deviation in a width direction of the sheet and a memberfor adjusting (vertically aligning) the deviation in a directionorthogonal to the width direction of the sheet. Particularly, withrespect to the deviation in the direction orthogonal to the widthdirection of the sheet, the deviation of the sheets loaded on theprocessing tray is aligned by using a vertical alignment member thatrotates around an axis of rotation extending in the width direction ofthe sheet.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an image forming system according to anembodiment;

FIG. 2 is an electrical block diagram illustrating an image formingapparatus and a sheet processing apparatus according to the presentembodiment;

FIG. 3 is a diagram schematically illustrating details of theconfiguration of each section of the sheet processing apparatusaccording to the present embodiment;

FIG. 4 is a diagram schematically illustrating a relation between astandby tray and a paddle section according to the present embodiment;

FIG. 5 is a diagram illustrating the paddle section according to thepresent embodiment;

FIG. 6 is a diagram illustrating standby positions of a first paddle anda second paddle according to the present embodiment;

FIG. 7 is a diagram illustrating a sheet moving processing (firstoperation) by the first paddle according to the present embodiment;

FIG. 8 is a diagram illustrating a vertical alignment processing (secondoperation) by the first paddle according to the present embodiment;

FIG. 9 is a diagram illustrating stop positions of the first paddle andthe second paddle according to the present embodiment;

FIG. 10 is a diagram illustrating a vertical alignment processing (thirdoperation) by the second paddle according to the present embodiment;

FIG. 11 is a diagram illustrating a state after the vertical alignmentprocessing is completed by the first paddle and the second paddleaccording to the present embodiment;

FIG. 12 is a diagram illustrating the standby positions of the firstpaddle and the second paddle after the vertical alignment processingaccording to the present embodiment;

FIG. 13 is a flowchart illustrating a processing for controllingrotation of the paddle section according to the present embodiment;

FIG. 14 is a timing chart illustrating a relation between time and speedof the paddle section according to the present embodiment;

FIG. 15 is a table illustrating a relation between the speed of thepaddle section and the type of a sheet according to another embodiment;and

FIG. 16 is a flowchart illustrating a setting processing of the speed ofthe paddle section according to sheet type information according to thepresent embodiment.

DETAILED DESCRIPTION

In accordance with the present embodiment, a sheet processing apparatuscomprises a standby section configured to buffer a sheet; a processingsection configured to receive sheets supplied from the standby sectionand execute a post processing on the sheets; a rotational shaftconfigured to rotate around an axis of rotation; a paddle arranged inthe rotational shaft and configured to contact the sheet and move thesheets by rotating with the rotational shaft, the paddle beingconfigured to slide the sheets on the processing section to a stopperfor aligning the sheets; and a controller configured to control arotational speed of the rotational shaft to rotate the paddle at a firstspeed, and control the rotational speed of the rotational shaft torotate the paddle at a second speed slower than the first speed whilethe paddle contacts the sheets on the processing section for aligning.

In accordance with another embodiment, a sheet processing methodinvolves receiving a plurality of sheets on a processing section;rotating a paddle around an axis of rotation at a first speed; androtating the paddle at a second speed slower than the first speed whilethe paddle contacts the sheets on the processing section for aligning byrotating with the axis of rotation.

Hereinafter, the sheet processing apparatus of the embodiment isdescribed with reference to the accompanying drawings. Furthermore, inthe following description, the same numerals are applied toconfigurations having identical or similar functions. Further, there isa case in which the repeated description of these configurations isomitted.

The sheet processing apparatus of a first embodiment is described withreference to FIG. 1 to FIG. 14. FIG. 1 is a diagram illustrating theentire configuration of an image forming system. FIG. 2 is an electricalblock diagram illustrating an image forming apparatus and a sheetprocessing apparatus. The image forming system contains an image formingapparatus 1 and a sheet processing apparatus 2. The image formingapparatus 1 forms an image on a sheet-like medium (hereinafter, referredto as a “sheet”) such as a paper. The sheet processing apparatus 2carries out a post processing on a sheet conveyed from the image formingapparatus 1.

The image forming apparatus 1 shown in FIG. 1 includes a control panel11, a scanner section 12, a printer section 13, a sheet feed section 14,a sheet discharge section 15 and an controller 16.

The control panel 11 has interface including various keys for receivingoperations of a user. For example, the control panel 11 receives aninput relating to a type of the post processing of the sheet. Thecontrol panel 11 sends information relating to the input type of thepost processing to the sheet processing apparatus 2.

The scanner section 12 includes a reading section for reading imageinformation of a copy object. The scanner section 12 sends the readimage information to the printer section 13.

The printer section 13 forms an image (hereinafter, referred to as a“toner image”) with a developing agent such as toner on the basis of theimage information sent from the scanner section 12 or an externaldevice. The printer section 13 transfers the toner image onto a surfaceof the sheet. The printer section 13 fixes the toner image by applyingheat and pressure to the toner image transferred onto the sheet.

The sheet feed section 14 supplies the sheets one by one to the printersection 13. The sheet discharge section 15 conveys the sheet from theprinter section 13 to the sheet processing apparatus 2.

As shown in FIG. 2, the controller 16 controls all operations of theimage forming apparatus 1. In other words, the controller 16 controlsthe control panel 11, the scanner section 12, the printer section 13,the sheet feed section 14 and the sheet discharge section 15. Thecontroller 16 is formed by a control circuit containing a CPU, a ROM anda RAM that are not shown.

Next, the configuration of the sheet processing apparatus 2 is describedwith reference to FIG. 1 and FIG. 2. As shown in FIG. 1, the sheetprocessing apparatus 2 is arranged adjacent to the image formingapparatus 1. The sheet processing apparatus 2 executes a post processingdesignated through the control panel 11 or the external device such asthe client PC on the sheet conveyed from the image forming apparatus 1.For example, the post processing includes a stapling processing or asorting processing.

The sheet processing apparatus 2 includes a standby section 21, aprocessing section 22, a discharge section 23 and a controller 24. Thestandby section 21 temporarily buffers a sheet S (refer to FIG. 3)conveyed from the image forming apparatus 1. For example, the standbysection 21 enables a plurality of succeeding sheets S to stand by whilethe post processing on the preceding sheet S is carried out by theprocessing section 22. The standby section 21 is arranged above theprocessing section 22. The standby section 21 enables the buffered sheetS to drop towards the processing section 22 if the sheet in theprocessing section 22 is discharged to the discharge section 23.

The processing section 22 carries out the post processing on the sheetS. For example, the processing section 22 carries out the staplingprocessing on a plurality of the aligned sheets S. In this way, aplurality of the sheets S is bound together by staples. The processingsection 22 discharges the sheet S to which the post processing iscarried out to the discharge section 23.

The discharge section 23 includes a fixed tray 23 a and a movable tray23 b. The fixed tray 23 a is arranged on the upper part of the sheetprocessing apparatus 2. The movable tray 23 b is arranged on the side ofthe sheet processing apparatus 2. The sheet S to which the staplingprocessing or the sorting processing is carried out is discharged to themovable tray 23 b.

As shown in FIG. 2, the controller 24 controls all operations of thesheet processing apparatus 2. In other words, the controller 24 controlsthe standby section 21, the processing section 22 and the dischargesection 23. Further, as shown in FIG. 2, the controller 24 controls aninlet roller 32 a, an exit roller 33 a, a paddle section 25 (or paddle)and a paddle motor 28. The controller 24 includes a control circuitcontaining a CPU, a ROM and a RAM that are not shown.

FIG. 3 illustrates a configuration of each section of the sheetprocessing apparatus 2. Furthermore, a “sheet conveyance direction”described in the present embodiment refers to a conveyance direction Dof the sheet S to the standby tray 211 of the standby section 21 (anapproach direction of the sheet S to a standby tray 211) or a directionin which the sheet S is conveyed from a processing tray 221 to themovable tray 23 b.

Further, an “upstream side” and a “downstream side” described in thepresent embodiment respectively refer to the upstream side and thedownstream side in the sheet conveyance direction D. Further, a “frontend part” and a “back end part” described in the present embodimentrespectively refer to “the end part of the downstream side” and “the endpart of the upstream side” in the sheet conveyance direction D. In thepresent embodiment, a direction orthogonal to the sheet conveyancedirection D is referred to as a sheet width direction W.

Hereinafter, the details of the configuration of each section of thesheet processing apparatus 2 are described based on FIG. 3. A conveyancepath 31 is a conveyance path from a sheet supply port 31 p to a sheetdischarge port 31 d. The sheet supply port 31 p is arranged at aposition facing the image forming apparatus 1. The sheet S is suppliedfrom the image forming apparatus 1 to the sheet supply port 31 p. On theother hand, the sheet discharge port 31 d is located in the vicinity ofthe standby section 21. The sheet S discharged from the image formingapparatus 1 is discharged to the standby section 21 via the conveyancepath 31.

The inlet rollers 32 a and 32 b are arranged in the vicinity of thesheet supply port 31 p. The inlet rollers 32 a and 32 b convey the sheetS supplied to the sheet supply port 31 p towards the downstream side ofthe conveyance path 31. For example, the inlet rollers 32 a and 32 bconvey the sheet S supplied to the sheet supply port 31 p to the exitrollers 33 a and 33 b.

The exit rollers 33 a and 33 b are arranged in the vicinity of the sheetdischarge port 31 d. The exit rollers 33 a and 33 b receive the sheet Sconveyed by the inlet rollers 32 a and 32 b. The exit rollers 33 a and33 b convey the sheet S from the sheet discharge port 31 d to thestandby section 21.

The standby section 21 includes the standby tray (buffer tray) 211, aconveyance guide 212, discharge rollers 213 a and 213 b and an openingand closing driving section (not shown).

The back end part of the standby tray 211 is located in the vicinity ofthe exit rollers 33 a and 33 b. The back end part of the standby tray211 is located slightly below the sheet discharge port 31 d of theconveyance path 31. The standby tray 211 is inclined with respect to thehorizontal direction in such a way as to gradually rise towards thedownstream side of the sheet conveyance direction D. The standby tray211 stacks a plurality of the sheets S to enable them to stand by whilethe post processing is carried out by the processing section 22.

FIG. 4 illustrates a relation between the standby tray 211 and thepaddle section 25 described later. As shown in FIG. 4, the standby tray211 includes a first tray member 211 a and a second tray member 211 b.The first tray member 211 a and the second tray member 211 b areseparated from each other in a sheet width direction W. The first traymember 211 a and the second tray member 211 b is driven by the openingand closing driving section and move in a mutually approaching directionand in a mutually separating direction.

The first tray member 211 a and the second tray member 211 b support thesheet S conveyed from the exit rollers 33 a and 33 b in a state in whichthe first tray member 211 a and the second tray member 211 b approacheach other. On the other hand, the first tray member 211 a and thesecond tray member 211 b are separated in the mutually separatingdirection in the sheet width direction W to enable the sheet S to movefrom the standby tray 211 towards the processing tray 221. In this way,the sheet S supported by the standby tray 211 drops from a space betweenthe first tray member 211 a and the second tray member 211 b towards theprocessing tray 221. In other words, the sheet S moves from the standbytray 211 to the processing tray 221.

An assist arm 41 shown in FIG. 3 is arranged above the standby tray 211.For example, the length of the assist arm 41 is approximately half ormore of that of the standby tray 211 in the sheet conveyance directionD. In the present embodiment, the assist arm 41 has the approximatelysame length as the standby tray 211 in the sheet conveyance direction D.The assist arm 41 is a plate-like member extending upwards the standbytray 211. The sheet S discharged from the exit rollers 33 a and 33 benters into the space between the assist arm 41 and the standby tray211.

The processing section 22 shown in FIG. 3 includes the processing tray221, a stapler 222, conveyance rollers 223 a and 223 b, and a conveyancebelt 224, a stopper 225 and a horizontal alignment plate 51.

The processing tray 221 is arranged below the standby tray 211. Theprocessing tray 221 is inclined with respect to the horizontal directionin such away as to gradually rise towards the downstream side of thesheet conveyance direction D. The processing tray 221 is inclinedapproximately parallel to the standby tray 211. As for a plurality ofsheets S moved to the processing tray 221, deviation between the sheetsS in the sheet width direction W is aligned by the horizontal alignmentplate 51.

The stapler 222 is arranged at an end part of the processing tray 221.The stapler 222 carries out a stapling (binding) processing on a bundleof the predetermined number of sheets S located on the processing tray221.

The conveyance rollers 223 a and 223 b are arranged at a predeterminedinterval in the sheet conveyance direction D. The conveyance belt 224 isstretched over the conveyance rollers 223 a and 223 b. The conveyancebelt 224 is rotated in synchronization with the conveyance rollers 223 aand 223 b. The conveyance belt 224 conveys the sheet S between thestapler 222 and the discharge section 23.

The stopper 225 is arranged at the upstream side of the sheet conveyancedirection when viewed from the conveyance roller 223 b. The stopper 225is a member for receiving an end of the sheets S moved from the standbytray 211 to the processing tray 221 to align them in the sheetconveyance direction. In other words, the stopper 225 is a memberserving as a sheet reference position when an alignment processing inthe sheet conveyance direction is executed. In other words, the sheets Smoved towards the upstream side of the sheet conveyance directionthrough a first paddle 25 a and a second paddle 25 b described later arestruck against the stopper 225 to be aligned in the sheet conveyancedirection. Hereinafter, aligning the sheets in the sheet conveyancedirection is referred to as a vertical alignment processing.

The paddle section 25 shown in FIG. 3 includes the first paddle 25 a,the second paddle 25 b, an rotational shaft 26 and a rotating body 27.

The rotational shaft 26 is a rotation center of the first paddle 25 aand the second paddle 25 b described later. The rotational shaft 26 islocated below the standby tray 211. The rotational shaft 26 extends inthe sheet width direction W. The rotational shaft 26 receives drivingforce from the paddle motor 28 to rotate in an arrow A direction (in acounter-clockwise direction) in FIG. 3.

FIG. 5 is a diagram illustrating the detailed configuration of thepaddle section 25. The paddle section 25 includes the first paddle 25 a,the second paddle 25 b and the rotating body 27.

The rotating body 27 is a cylindrical shape with a part of regionmissed. The rotating body 27 includes a protrusion 271. The protrusion271 is fitted into a groove preset in the rotational shaft 26 to bedetachably mounted in the rotational shaft 26. If the rotational shaft26 is rotated in the rotation direction A (in the counter-clockwisedirection) in FIG. 3, the rotating body 27 is also rotated integrally inthe same direction. Further, as the first paddle 25 a and the secondpaddle 25 b are mounted in the rotating body 27, if the rotational shaft26 is rotated in the arrow A direction in FIG. 3, the first paddle 25 aand the second paddle 25 b are rotated in the counter-clockwisedirection together with the rotating body 27.

The first paddle 25 a and the second paddle 25 b are formed with anelastic material such as rubber or resin. The first paddle 25 aprotrudes to the diameter direction of the rotating body 27 to bemounted in the rotating body 27. The first paddle 25 a has a length L1in the diameter direction of the rotating body 27. The first paddle 25 ahas a shape in which a thickness d1 at the mounting position to therotating body 27 is different from a thickness d2 of the front end ofthe paddle. In detail, the first paddle 25 a has the thickness d1 in aregion from the mounting position x0 to the rotating body 27 to aposition x1 protruding in the diameter direction of the rotating body27. The first paddle 25 a has a shape in which the thickness d1 isgradually decreased towards the position x2 in the region from theposition x1 to the position x2. The first paddle 25 a has the thicknessd2 (<d1) in the region from the position x2 to the position x3. Thefirst paddle 25 a ensures the strength thereof due to the thickness dlbetween the position XO and the position X1. By contrast, a noisegenerated by contact of the first paddle 25 a against the sheetsupported by the stand-by tray 211 (as shown in FIG. 7) is reduced dueto the thickness d2 thinner than dl between the position X2 and theposition X3. Furthermore, a noise generated by contact of the firstpaddle 25 a against the sheet supported by the processing tray 221 (asshown in FIG. 8) is reduced due to the thickness d2 thinner than d1between the position X2 and the position X3.

As shown in FIG. 5, the second paddle 25 b is arranged to have apredetermined angle with respect to the first paddle 25 a. In otherwords, the second paddle 25 b is arranged to have a predetermineddistance away from the rear of the first paddle 25 a in the rotationdirection A in FIG. 3.

The second paddle 25 b protrudes to the diameter direction of therotating body 27 to be amounted in the rotating body 27. The secondpaddle 25 b has a length L2 shorter than the length L1 of the firstpaddle 25 a in the diameter direction of the rotating body 27. Further,the second paddle 25 b has a shape in which the thickness dl at themounting position to the rotating body 27 is thicker than the thicknessd2 of the front end of the paddle, which is identical to the firstpaddle 25 a. The shape of the second paddle 25 b is identical to that ofthe first paddle 25 a, and thus the description thereof is omitted.

A series of operations of the first paddle 25 a and the second paddle 25b is described with reference to FIG. 6 to FIG. 12.

FIG. 6 is a diagram illustrating standby positions before the firstpaddle 25 a and the second paddle 25 b are driven to rotate. The“standby positions” refer to positions at which the first paddle 25 aand the second paddle 25 b stand by when the sheet S is conveyed fromthe exit rollers 33 a and 33 b towards the standby tray 211 to bestacked or the sheet S is directly conveyed from the exit rollers 33 aand 33 b to the processing tray 221. In other words, the “standbypositions” refer to the positions where the first paddle 25 a and thesecond paddle 25 b wait when the first paddle 25 a and the second paddle25 b do not carry out the vertical alignment processing on the sheets.

In FIG. 6, the first paddle 25 a is arranged at a position at which thefirst paddle 25 a does not protrude towards the downstream side of thesheet conveyance direction D with respect to the outer peripheralsurface of the exit roller 33 b when viewed from an axis 33 c of theexit roller 33 b. From a different point of view, when viewed from thestandby tray 211, the first paddle 25 a is located at the upstream sideof the conveyance direction with respect to the outer peripheral surfaceof the exit roller 33 b located in the vicinity of the standby tray 211and is arranged at a position at which the conveyance of the sheet Sconveyed from the exit roller 33 b to the standby tray 211 is notdisturbed. The second paddle 25 b is arranged at a position at which thefront end part thereof is apart from the sheets S on the processing tray221 at only a predetermined distance.

FIG. 7 illustrates a state in which the first paddle 25 a contacts withthe sheet S to be moved from the standby tray 211 to the processing tray221. If the predetermined number of sheets S is stacked on the standbytray 211, the controller 24 drives a pair of the standby tray members211 a and 211 b in the mutually separating direction in the sheet widthdirection W to move the buffered sheets S to the processing tray 221.

The controller 24 drives the paddle motor 28 to rotate the rotationalshaft 26. The first paddle 25 a is rotated with the rotation of therotational shaft 26 and contact with the sheet S dropped from thestandby tray 211 at a speed V1. Then the first paddle 25 a forces thesheets S towards the processing tray 221. An operation, that is, thefirst paddle 25 a contacts with the sheet S to move the sheet S from thestandby tray 211 to the processing tray 221, is referred to as a firstoperation.

FIG. 8 illustrates an operation of the vertical alignment processing tothe sheets S on the processing tray 221 by the first paddle 25 a throughthe further rotation of the first paddle 25 a in the arrow A direction(in the counter-clockwise direction).

The first paddle 25 a is further rotated in the arrow A direction toguide the sheet S onto the processing tray 221 and contacts with theprocessing tray 221 across the sheet S to become a bent state (refer toFIG. 8) from the state shown in FIG. 7. The first paddle 25 a is rotatedin the arrow A direction at a speed V2 to be kept in the bent state andmoves the sheet S towards the stopper 225 located at the upstream sideof the sheet conveyance direction from the processing tray 221. In otherwords, the first paddle 25 a sandwiches a plurality of the sheets Stogether with the processing tray 221 and draws the sheets S into thestopper 225 to carry out the vertical alignment processing. Theoperation of carrying out the vertical alignment processing on thesheets S by the first paddle 25 a is referred to as a second operation.

FIG. 9 illustrates states of the first paddle 25 a and the second paddle25 b after the vertical alignment processing on the sheets S by thefirst paddle 25 a shown in FIG. 8.

The controller 24 controls rotation of the rotational shaft 26 tosuspend the first paddle 25 a and the second paddle 25 b after the firstpaddle 25 a separates from the sheets and before the second paddle 25 bcontacts with the sheets. The controller 24 controls the paddle motor 28to stop the rotation of the rotational shaft 26 if the first paddle 25 aarrives at a position away from the sheets S on the processing tray 221after the first paddle 25 a executes the vertical alignment processingon the sheets S. In this way, the rotation of the first paddle 25 a andthe second paddle 25 b is stopped. The second paddle 25 b is stopped insuch a way as to be positioned at the position away from the sheets S onthe processing tray 221 at only the predetermined distance. In otherwords, after the vertical alignment processing on the sheets S iscarried out by the first paddle 25 a, the first paddle 25 a and thesecond paddle 25 b are controlled to stop the rotation operation thereofin such a way as to be mutually positioned at the positions away fromthe sheets S on the processing tray 221 at only the predetermineddistance.

The reason why the first paddle 25 a and the second paddle 25 b arestopped at the positions away from the sheets S on the processing tray221 at only the predetermined distance is described as follows. Afterthe vertical alignment processing is carried out on the sheets S by thefirst paddle 25 a, a processing (horizontal alignment processing) ofaligning the end parts of the width direction of the sheets in the sheetwidth direction W is executed by the horizontal alignment plate 51. Atthe time of the horizontal alignment processing, if the first paddle 25a or the second paddle 25 b contacts with the sheet S, the processing(horizontal alignment processing) of aligning the end parts of the widthdirection of the sheets is disturbed, and thus the first paddle 25 a andthe second paddle 25 b are separated from the sheet S.

FIG. 10 illustrates the operation of the vertical alignment processingof the sheets S by the second paddle 25 b. The controller 24 controlsthe drive of the paddle motor 28 to rotate the first paddle 25 a and thesecond paddle 25 b again in the arrow A direction at a speed V3. Thefirst paddle 25 a and the second paddle 25 b receive the drive force ofthe paddle motor 28 to rotate in the counter-clockwise direction.

Hereinafter, the second paddle 25 b is concentratedly described. Thesecond paddle 25 b contacts with the sheet S in the bent state to carryout a drawing-in operation towards the stopper 225. The operation ofcarrying out the vertical alignment processing on the sheet S by thesecond paddle 25 b is referred to as a third operation.

The reason why the vertical alignment processing is further carried outthrough the second paddle 25 b is described as follows. When the firstpaddle 25 a draws the sheet S into the stopper 225, there is a case inwhich a drawing-in quantity of the sheets S becomes excessive. Thedrawing-in quantity of the sheets amounts to a force to slide a sheet onthe processing tray 211 towards to the stopper 225 by the first paddle25 a or the second paddle 25 b. In this case, the sheets S strikeagainst the stopper 225 and move towards the sheet conveyance directionD through repulsive force, and there is a possibility that the alignmentof the sheets S in the sheet conveyance direction cannot be executedwith high accuracy. Thus, after the first paddle 25 a carries out thedrawing-in operation of the sheet S, the second paddle 25 b carries outthe drawing-in operation again to execute the vertical alignmentprocessing again on the sheets S to which the vertical alignmentprocessing cannot be sufficiently carried out by the first paddle 25 a,and it is possible to improve the aligning state in the sheet conveyancedirection. While the first paddle 25 a makes one rotation, it ispossible to execute the vertical alignment processing twice by the firstpaddle 25 a and the second paddle 25 b, which contributes to the highspeed of the sheet processing without the need of rotating the paddlesection for many times.

Furthermore, the drawing-in quantity of the sheets S by the secondpaddle 25 b may be smaller than that by the first paddle 25 a becausethe first paddle 25 a has already executed the vertical alignmentprocessing before the second paddle 25 b contact with the sheet on theprocessing tray 221. For example, the length L2 of the second paddle 25b may be shorter than the length L1 of the first paddle 25 a as statedabove. Hereby, the area where the sheets S and the second paddle 25 bcontact with each other is smaller than the area where the sheets S andthe first paddle 25 a contact with each other. Therefore, it is possiblethat the drawing-in quantity of the sheets S by the second paddle 25 bis smaller than that of the sheets S by the first paddle 25 a.

Furthermore, in one embodiment the Young's modulus of materials of thesecond paddle 25 b may be smaller than that of the first paddle 25 a sothat the stress generated due to the bend of the second paddle 25 b issmaller than that generated due to the bend of the first paddle 25 a.Also, as for the hardness of the first paddle 25 a and the second paddle25 b, in one embodiment the second paddle 25 b may be softer than thefirst paddle 25 a. Further, as for the relation between the thicknessesof the first paddle 25 a and the second paddle 25 b, in one embodimentthe second paddle 25 b may be thinner than the first paddle 25 a.Particularly, it is preferable that apart of second paddle 25 b wherethe second paddle 25 b contact with the sheet on the processing tray 221is thinner than a part of the first paddle 25 a where the first paddle25 a contact with the sheet on the processing tray 221.

FIG. 11 is a diagram illustrating a state after the vertical alignmentprocessing is completed by the first paddle 25 a and the second paddle25 b.

After the vertical alignment processing is executed by the second paddle25 b, the first paddle 25 a and the second paddle 25 b stop afterrotating to the positions indicated by solid lines in FIG. 11. Dottedlines shown in FIG. 11 indicate the standby positions (refer to FIG. 6)of the first paddle 25 a and the second paddle 25 b. The controller 24rotates the first paddle 25 a and the second paddle 25 b to thepositions (positions indicated by the solid lines) exceeding the standbypositions after the vertical alignment processing by the second paddle25 b to certainly separate the second paddle 25 b after the verticalalignment processing from the sheets S on the processing tray 221. Inthis way, the second paddle 25 b stops in a state where it contacts withthe sheets Son the processing tray 221, and it is suppressed that anegative influence is applied to sheet aligning properties at the timesucceeding sheets are conveyed to the processing tray.

Then, the controller 24 controls the paddle motor 28 to rotate in adirection (in a clockwise direction) opposite to the arrow A directionand positions the first paddle 25 a and the second paddle 25 b at thestandby positions.

FIG. 12 is a diagram illustrating a state where the first paddle 25 aand the second paddle 25 b return to the standby positions. The firstpaddle 25 a and the second paddle 25 b wait for that the succeedingsheets are received by the standby tray 211 in a state where they arelocated at the standby positions.

Next, the concrete control of the speed at the time of a series ofoperations of the paddle section shown in FIG. 13 to FIG. 14 isdescribed.

FIG. 13 is a flowchart illustrating a processing for controlling thepaddle section 25 (the first paddle 25 a and the second paddle 25 b) bythe controller 24. FIG. 14 is a timing chart in which the horizontalaxis indicates time and the vertical axis indicates the speed of thepaddle section 25 (the first paddle 25 a and the second paddle 25 b).Furthermore, in the following description, there is also a case in whichthe paddle section 25 (the first paddle 25 a and the second paddle 25 b)is simply referred to as the paddle section 25.

The controller 24 forward rotates the paddle motor 28 to control thepaddle section 25 to rotate in the counter-clockwise direction withrespect to the axis of rotation of the rotational shaft 26. Further, thecontroller 24 backward rotates the paddle motor 28 to control the paddlesection 25 to rotate in the clockwise direction with respect to the axisof rotation of the rotational shaft 26.

Firstly, if a plurality of sheets is buffered on the standby tray 211,the controller 24 drives the paddle motor 28 to forward rotate (Act 101)to rotate the paddle section 25 in the counter-clockwise direction atthe speed V1 (Act 102). The paddle section 25 receives the driving forceof the paddle motor 28 to be accelerated, and after the speed thereofreaches the speed V1, maintains the speed V1 to rotate until reaching apreset angle (for a period from time 0 to time t1 shown in FIG. 14). Thefirst paddle 25 a contacts with the sheet to be moved from the standbytray 211 to the processing tray 221 at the speed V1 to give assistancein order to accelerate the movement of the sheet to the processing tray(refer to FIG. 7). In other words, the first paddle 25 a of the paddlesection 25 executes the first operation at the speed V1.

Next, the controller 24 determines whether or not the paddle section 25is rotated at a preset angle θ1 from the standby position (refer to FIG.6) in the counter-clockwise direction (Act 103). If it is determinedthat the paddle section 25 is rotated at the preset angle θ1 (Yes in Act103), the controller 24 controls the drive of the paddle motor 28 whilethe speed of the paddle section 25 becomes the speed V2 slower than thespeed V1 (Act 104). In other words, the paddle section 25 is graduallydecelerated from the speed V1 to the speed V2, and if the speed reachesthe V2, continuously rotates at the speed V2 until reaching a presetangle θ2 (for a period from the time t1 to time t2 shown in FIG. 14). Atthis time, the first paddle 25 a carries out the vertical alignmentprocessing serving as the second operation on the sheets S moved to theprocessing tray 221 at the speed V2 (refer to FIG. 8). The controller 24enables the first paddle 25 a to contact with the sheets on theprocessing tray 221 at the speed V2 slower than the speed V1 to executethe vertical alignment processing to suppress slipping at the time thefirst paddle 25 a contacts with the surface of the sheet and align theend parts of the sheets in the sheet conveyance direction with highaccuracy.

The controller 24 determines whether or not the paddle section 25 isrotated at the preset angle θ2 (>θ1) from the standby position (refer toFIG. 6) (Act 105). If it is determined that the paddle section 25 isrotated at the preset angle 02 (Yes in Act 105), the controller 24controls the drive of the paddle motor 28 to stop the rotation of thepaddle section 25. In this way, the paddle section 25 temporarily stopsthe rotation (Act 106). In other words, the paddle section 25 isgradually decelerated to the speed 0 from the speed V2 (for a periodfrom the time t2 to time 3 shown in FIG. 14).

After that, the paddle section 25 is positioned at a position away fromthe sheets on the processing tray to be stopped as shown in FIG. 9 (fora period from the time t3 to time t4 shown in FIG. 14).

After the rotation of the paddle section 25 is temporarily stopped, thecontroller 24 determines whether or not a predetermined time elapses(Act 107). If it is determined that the predetermined time elapses (Yesin Act 107), the controller 24 drives the paddle motor 28 to forwardrotate again (Act 108), the paddle section 25 is rotated at the speed V3slower than the speed V2 in the counter-clockwise direction (Act 109).The paddle section 25 is gradually accelerated to the speed V3 from thestop state, and if the speed reaches the V3, continuously rotates at thespeed V3 until reaching a preset angle θ3 (>θ2). The second paddle 25 bof the paddle section 25 carries out the vertical alignment processingserving as the third operation on the sheets moved to the processingtray 221 at the speed V3 as shown in FIG. 10 (for a period from the timet4 to time t5 shown in FIG. 14). Next, the controller 24 determineswhether or not the paddle section 25 is rotated at the preset angle 03from the standby position (refer to FIG. 6) in the counter-clockwisedirection (Act 110). If it is determined that the paddle section 25 isrotated at the preset angle θ3 (Yes in Act 110), the controller 24controls the drive of the paddle motor 28 to stop the rotation of thepaddle section 25 (Act 111). In other words, the paddle section 25 isgradually decelerated to the speed 0 from the speed V3 (for a periodfrom the time t5 to time t6 shown in FIG. 14).

The controller 24 stops the rotation of the paddle section 25 (ACT 111).The paddle section 25 is positioned at a position only for apredetermined time where the paddle section 25 moves at a predeterminedangle from the standby position indicated by the dotted line in FIG. 11in the counter-clockwise direction (for a period from the time t6 totime t7 shown in FIG. 14). The paddle section 25 often moves at thepredetermined angle to prevent that the paddle section 25 is maintainedon the processing tray 221 in the bent state and prevent that theinfluence is applied to the sheet S aligning properties on theprocessing tray 221.

The controller 24 drives the paddle motor 28 to backward rotate torotate the paddle section 25 at an angle 00 in the clockwise direction(Act 112). If it is determined that the paddle section 25 is rotated atan angle θ0 (Yes in Act 113), the controller 24 stops the paddle section25. The paddle section 25 is rotated at a speed −V4 from the stop state(for a period from the time t7 to time t8 shown in FIG. 14).

If it is determined that the paddle section 25 is rotated at an angle θ0in the clockwise direction (Yes in Act 113), the controller 24 stops thebackward rotation to stop a series of operations (Act 114).

Furthermore, in the foregoing description, it is described that thecontroller 24 switches the speed of the paddle section 25 based on theangle at which the paddle section 25 is rotated; however, the referenceof the change of the speed is not limited to this. For example, thespeed of the paddle section 25 may be changed based on the number ofsteps of the paddle motor 28.

According to the present embodiment, it is possible that the speed V1 atthe time of the first operation of moving the sheet S from the standbytray 211 to the processing tray 221 is set to a speed quicker than thespeed V2 at the time of the second operation of carrying out thevertical alignment processing on the sheets S placed on the processingtray 221 to shorten the processing time when the sheet S is moved fromthe standby tray 211 to the processing tray 221.

Further, from another point of view, by setting the speed V2 at the timeof the second operation to the speed slower than the speed V1 at thetime of the first operation, it is possible to suppress the slipping atthe time the first paddle 25 a contacts with the surface of the sheet Sand execute the vertical alignment processing with high accuracy.

According to the present embodiment, by setting the speed V3 at the timeof the third operation of carrying out the vertical alignment processingon the sheets S placed on the processing tray 221 after the secondoperation to the speed slower than the speed V1 at the time of the firstoperation and the speed V2 at the time of the second operation, it ispossible to certainly contact the paddle section 25 with the sheets S toexecute the vertical alignment processing of the sheets S.

Second Embodiment

A sheet processing apparatus 2 of the second embodiment, in addition tothe configuration of the sheet processing apparatus 2 of the firstembodiment, includes a function of setting a rotational speed of thepaddle section 25 according to the type of the sheet by the controller24.

If the paddle section 25 carries out the vertical alignment processingon the sheets at the same speed regardless of the types of the sheets(size, grammage and the like), there is a case in which the forceapplied by the paddle section is not sufficient according to the typesof the sheets, and a case of leading to misalignment is also considered.

According to the sheet processing apparatus 2 of the second embodiment,the speed of the paddle section 25 is changed according to the types ofthe sheets such as the size or the grammage of the sheet, and thus thepaddle section 25 is possible to execute the vertical alignmentprocessing with high accuracy.

FIG. 15 is a table 150 illustrating a relation between the types of thesheets and the speeds of the paddle section 25. Information shown in thetable 150 of FIG. 15 is stored in, for example, the RAM in thecontroller 24 in advance.

The middle row 1501 of the table 150 indicates that the paddle section25 respectively executes the first operation at the speed V1, the secondoperation at the speed V2 and the third operation at the speed V3correspondingly in a case in which the sheet serving as an objectprocessed by the sheet processing apparatus 2 is a plain paper. On theother hand, the lower row 1502 of the table 150 indicates that thepaddle section 25 respectively executes the first operation at a speedV1′, the second operation at a speed V2′ and the third operation at aspeed V3′ correspondingly in a case in which the sheet serving as anobject processed by the sheet processing apparatus 2 is a thick paper.

The relation between the speed of the paddle section 25 in the case ofthe plain paper and that in the case of the thick paper is set to thefollowing relation: V1>V1′, V2>V2′ and V3>V3′. In other words, even inany operation of the first operation, the second operation and the thirdoperation carried out by the paddle section 25, it is set that the speedwhen the paddle section 25 carries out the operation on the thick paperis slower than that the paddle section 25 carries out the operation onthe plain paper. In other words, the larger the grammage of the sheetis, the slower the rotational speed of the paddle section 25 is.

The reason why the speed is set in this way is as follows. The grammageof the thick paper is larger than that of the plain paper, and thus thepaddle section 25 needs larger force to move the thick paper towards thestopper compared with the case of the plain paper. Therefore, by settingthe speed of the paddle section 25 in the case of the thick paper to beslower than that in the case of the plain paper, it is possible totransfer the force acting on the sheet by certainly contacting thepaddle section 25 with the sheet.

FIG. 16 is a flowchart illustrating a setting processing of the speed ofthe paddle section 25 corresponding to sheet type information, which isexecuted by the controller 24. The controller 24 determines whether ornot the sheet type information of the thick paper is received from theimage forming apparatus 1 (Act 201). If the sheet type information ofthe thick paper is received (Yes in Act 201), the controller 24respectively sets the speed at the time of the first operation of thepaddle section 25 to the V1′, the speed at the time of the secondoperation thereof to the V2′ and the speed at the time of the thirdoperation thereof to the V3′ according to the table in FIG. 15 (Act202).

On the other hand, if the sheet type information of the thick paper isnot received (No in Act 201), the controller 24 respectively sets thespeed at the time of the first operation of the paddle section 25 to theV1, the speed at the time of the second operation thereof to the V2 andthe speed at the time of the third operation thereof to the V3 accordingto the table in FIG. 15 (Act 203). The setting processing of the speedof the paddle section 25 is completed through the foregoing processingin Act 201-Act 203. Furthermore, the speed in the case of the plainpaper may be set to a default value in advance.

After that, the controller 24 enables the paddle section 25 to operateaccording to the control shown in FIG. 13 at the speed set in thesetting processing in FIG. 16. For example, if the controller 24receives the information set as the thick paper, the speed is set as thespeed V1′ in ACT 102, the speed is set as the speed V2′ in ACT 104 andthe speed is set as the speed V3′ in ACT 109 in FIG. 13, and the paddlesection 25 executes the corresponding operation at the correspondingspeed.

According to the second embodiment, in a case in which the grammage ofthe sheet is larger than a preset grammage, by setting the speed of thepaddle section 25 to be slower, it is possible to suppress the slippingof the paddle section 25 contacting with the sheet at the time of thevertical alignment processing serving as the second operation of thepaddle section 25 and obtain a fine alignment state.

Furthermore, in the foregoing description, it is exemplified that thespeed of the paddle section 25 is set according to the grammage of thesheet; however, the present invention is not limited to this. Forexample, the present embodiment may be an embodiment in which the speedof the paddle section 25 is set according to the size of the sheet. Inthis case, if the size of the sheet is larger than a preset size of thesheet, the speed of the paddle section 25 is set to be slower than thepreset speed.

In this way, by setting the speed of the paddle section 25 to a speedslower than the speed set according to the preset size of the sheet, thepaddle section 25 and the sheet can certainly contact with each other,and the force acting on the sheet can be transferred.

Through the above, according to the second embodiment, as the speed ofthe paddle section is changed according to the type of the sheet, it ispossible to suppress the slipping of the paddle section contacting withthe sheet S. Further, the proper alignment quantity can be obtainedaccording to the type of the sheet.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the invention. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinvention. The accompanying claims and their equivalents are intended tocover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. An image forming system, comprising: a sheetfeeding section configured to supply sheets one by one; a printerconfigured to form an image on the sheet supplied by the sheet feedingsection; a sheet discharge section configured to convey the sheet fromthe printer; a processor that executes operations retained in a memory;a standby section configured to buffer a sheet from the sheet dischargesection; a sheet processing section configured to receive sheetssupplied from the standby section and execute a post processing on thesheets; a rotational shaft configured to rotate around an axis ofrotation; a paddle arranged in the rotational shaft and configured tocontact the sheets on the standby section and move the sheets from thestandby section to the processing section by rotating with therotational shaft, the paddle being configured to slide the sheets on theprocessing section to a stopper for aligning the sheets; and acontroller configured to control a rotational speed of the rotationalshaft to rotate the paddle at a first speed while the paddle moves thesheets from the standby section to the processing section, and controlthe rotational speed of the rotational shaft to rotate the paddle at asecond speed that is slower than the first speed while the paddlecontacts the sheets on the processing section for aligning and while thepaddle moves the sheet on the processing section to the stopper foraligning.
 2. The image forming system according to claim 1, wherein thepaddle is configured to contact the sheets on the standby section andmove the sheets from the standby section to the processing section, andthe controller is further configured to control the rotational speed ofthe rotational shaft to rotate the paddle at the first speed while thepaddle moves the sheets from the standby section to the processingsection, and control the rotational speed of the rotational shaft torotate the paddle at the second speed while the paddle moves the sheeton the processing section to the stopper for aligning.
 3. The imageforming system according to claim 2, wherein the paddle is a firstpaddle, further comprising: a second paddle arranged in the rotationalshaft at a predetermined angle with respect to the first paddle andconfigured to contact the sheets on the processing section and slide thesheets to the stopper by rotating with the rotational shaft for aligningthe sheet while the first paddle makes one rotation around the axis ofrotation, wherein the controller is configured to control the rotationalspeed of the rotational shaft to rotate the second paddle at a thirdspeed slower than the first speed while the second paddle moves thesheet on the processing section to the stopper for aligning.
 4. Theimage forming system according to claim 3, wherein the third speed isslower than the second speed.
 5. The image forming system according toclaim 4, wherein the controller changes the first speed, the secondspeed and the third speed according to types of the sheets.
 6. The imageforming system according to claim 5, wherein the controller carries outcontrol in such a manner that the larger a grammage of the sheet is, theslower the rotational speed is.
 7. The image forming system according toclaim 3, wherein the controller is further configured to controlrotation of the rotational shaft rotating the first paddle and thesecond paddle to suspend the first paddle and the second paddle afterthe first paddle separates from the sheets and before the second paddlecontacts with the sheets.
 8. A sheet processing method, comprising:forming an image on a sheet by a printer; conveying the sheet from theprinter; receiving a plurality of sheets on a processing section;rotating a paddle around an axis of rotation at a first speed; androtating the paddle at a second speed slower than the first speed whilethe paddle contacts the sheets on the processing section for aligning byrotating with the axis of rotation.
 9. The sheet processing methodaccording to claim 8, wherein contacting the sheets on the standbysection by the paddle; rotating the paddle at the first speed while thepaddle moves the sheets from the standby section to the processingsection, and rotating the paddle at the second speed while the paddlemoves the sheet on the processing section to a stopper for aligning. 10.The sheet processing method according to claim 9, wherein the paddle isa first paddle, the method further comprising: contacting the sheets onthe processing section by a second paddle by rotating with the axis ofrotation; and rotating the second paddle at a third speed slower thanthe first speed to move the sheet on the processing section to thestopper for aligning while the first paddle makes one rotation aroundthe axis of rotation.
 11. The sheet processing method according to claim10, wherein the third speed is slower than the second speed.
 12. Thesheet processing method according to claim 11, further comprising:changing the first speed, the second speed and the third speed accordingto types of the sheets.
 13. The sheet processing method according toclaim 12, wherein when a grammage of the sheet becomes larger, therotational speed of the paddle becomes slower.
 14. The sheet processingapparatus according to claim 10, further comprising: suspending thefirst paddle and the second paddle after the first paddle separates fromthe sheets and before the second paddle contacts with the sheets.